Agricultural vehicles, such as tractors and combines, are ubiquitous in the agricultural industry. As an agricultural vehicle travels across a field, agricultural processes such as plating and/or fertilizing are performed by an implement associated with the vehicle. One particular class of implements, such as seed planters, incorporate a disc opener to open a seed trench in which to plant the seed. Efficient crop growth requires that seeds be planted in different manners that depend at least in part upon soil conditions, fertilizer employed, seed type, and anticipated weather and sun exposure conditions. To this end, a seed planter trench opener disc must be capable of opening a seed trench to a selected depth and accurately placing seeds therein to assure that the seed is properly positioned in the soil.
Existing seed planters include various types of depth adjusting mechanisms to control trench depth. One particularly useful type of depth adjusting mechanism provides gauge wheels that, when in a depth adjusting position, have a bottom wheel surface that generally resides proximate and vertically above the bottom disc edge of an associated trenching opener disc. Here, the wheel travels along a field surface and therefore limits disc depth into the soil. In many cases a plurality of disc openers are each independently mounted to a support bar for towing behind a tractor or the like and a separate gauge wheel is mounted to each of the disc openers via an adjustable linkage mechanism so that the vertical height difference (hereinafter “the surface-edge difference”) between the bottom wheel surface and the bottom disc edge is adjustable. For instance, an exemplary disc-wheel configuration may be adjustable so that the surface-edge difference can be set in increments to between one and five inches.
Unfortunately, most depth control mechanisms of the type described above have one or more shortcomings. For instance, some depth control mechanisms of the above type have poorly located depth adjustments that make it difficult for an operator to access the adjusting mechanism. Some adjusting mechanisms require an operator to perform complex manipulations and to assume awkward positions when performing adjustments. Other adjusting mechanisms utilize a threaded shaft that takes a large amount of time to adjust and that has a tendency to seize up due to rust or become bound up due to accumulation of field debris. Still other adjusting mechanisms utilize one or a plurality of nut and bolt pairs to facilitate adjustment, these mechanisms often require two hands and are time consuming to manipulate. Moreover, many mechanisms require a large number of complex components that have small tolerances, are relatively expensive to manufacture, and assemble, and are expensive to maintain and replace when damaged. Furthermore, some mechanisms are difficult to manipulate because the mechanical advantage afforded by the mechanism designs is less than optimal. In addition, at least some prior mechanisms have increased the width of an associated seeding row unit disadvantageously.
On the other hand, in the case of depth control mechanisms that are easy to operate, it is often possible to easily disengage the depth control mechanisms during the seeding operation in the field, which can result in seeds being planted at the improper trench depth. For example, these mechanisms can be disengaged by debris and other residue material that is kicked up from the soil during operation. Moreover, in the case of mechanisms that rely on biasing springs to provide an the locking force and thereby reduce the difficulty of actuation, these springs can weaken over time so that only very little force is needed to disengage the mechanism. Therefore, debris and other residue material can easily overcome the spring force of the weakened springs and allow for undesired trench depth.
Thus, it would be advantageous to have a seed planter disc opener system that is capable of being positively-locked to prevent accidental disengagement by debris, that provides a conveniently located depth control mechanism, that is easy to operate, that requires minimal, simple, and robust components, and that is inexpensive to manufacture, assemble, and maintain.